What is a Kelvin wave, and how could it affect B.C.?

A Kelvin wave is a bulge in the ocean caused by a burst of westerly winds. It can intensify El Niño, potentially affecting conditions in B.C. Environment and Climate Change Canada research scientist Bill Merryfield told Daily Hive that Kelvin waves form along the Pacific equator toward the Asian side. Winds there generally blow from east to west; when something interrupts or reverses them, they push the ocean and create the bulge. Satellites can measure Kelvin waves, although they cannot be seen with the naked eye.

Early reports suggested the wave would reach B.C. in mid-October. Merryfield said it is now somewhere in the California region and is expected to reach B.C.’s shores in a week or two. The journey from where it forms in the far eastern Pacific along the equator takes about three months, he said. Merryfield called it “quite remarkable” that a burst of wind can set something travelling about 20,000 kilometres in motion. Near California, the wave has raised sea levels by about 20 to 40 centimetres.

Daily Hive has previously reported on king tides. In combination with the Kelvin wave, they could create treacherous conditions along B.C.’s coast as the wave affects provincial sea levels in a week or two. Merryfield said the last time this happened “in a very big way” was during a super El Niño in the late 1990s.

Merryfield warned that as winter approaches, the El Niño-related sea-level rise could persist for several weeks. Combined with king tides, it could bring coastal flooding and erosion worse than usual. B.C. is already expecting a mild winter, and the wave could add warmth to coastal areas during the season.